1762, the average concert pitch began rising from a low of 377 vibrations to a high of 457 in 1880 Vienna. Different regions, countries, and even instrument manufacturers preferred different standards, making orchestral collaboration a challenge. Despite even the efforts of two organized international summits attended by noted composers like Hector Berlioz, no standard could be agreed upon. Twentieth century to present The evolution of traditional musical instruments slowed beginning in the 20th century. Instruments such as the violin, flute, french horn, and harp are largely the same as those manufactured throughout the eighteenth and nineteenth centuries. Gradual iterations do emerge; for example, the "New Violin Family" began in 1964 to provide differently sized violins to expand the range of available sounds. The slowdown in development was a practical response to the concurrent slowdown in orchestra and venue size. Despite this trend in traditional instruments, the development of new musical instruments exploded in the twentieth century, and the variety of instruments developed overshadows any prior period. The proliferation of electricity in the 20th century led to a new category of musical instruments: electronic instruments, or electrophones. The vast majority produced in the first half of the 20th century were what Sachs called "electromechanical instruments"; they have mechanical parts that produce sound vibrations picked up and amplified by electrical components. Examples include Hammond organs and electric guitars. Sachs also defined a subcategory of "radioelectric instruments" such as the theremin, which produces music through the player's hand movements around two antennas. The latter half of the 20th century saw the evolution of synthesizers, which produce sound using circuits and microchips. In the late 1960s, Bob Moog and other inventors developed the first commercial synthesizers, such as the Moog synthesizer. Whereas once they had filled rooms, synthesizers can now be embedded in any electronic device, and are ubiquitous in modern music. Samplers, introduced around 1980, allow users to sample and reuse existing sounds, and were important to the development of hip hop. 1982 saw the introduction of MIDI, a standardized means of synchronizing electronic instruments. The modern proliferation of computers and microchips has created an industry of electronic musical instruments. Classification There are many different methods of classifying musical instruments. Various methods examine aspects such as the physical properties of the instrument (material, color, shape, etc.), the use for the instrument, the means by which music is produced with the instrument, the range